1. Subject Matter
This invention relates to improved drum closure assemblies and to the drum containers produced by their use.
2. Prior Art
This invention relates to an improved drum closure assembly and a method for securing the closure assembly to the open or top end of a drum body.
The drum which will be referred to in this application is a fibreboard drum of tubular form, which may be of laminated or nonlaminated structure. This type of fibreboard drum and the method for manufacturing same are disclosed in U.S. Pat. No. 3,039,371 to Leibreich. The primary advantage of fibreboard drums is that they can be manufactured in tubular form and then shipped or stored in flat form, thus presenting a substantial savings in terms of space usage. For the purpose of this application, these fibreboard drums are sometimes referred to as "KD Drums", the KD standing for "Knocked Down" which is simply descriptive of the condition in which the tubular fibreboard drums can be shipped and stored.
As can be appreciated, these drums are available in a variety of sizes, shapes, thicknesses and for a number of purposes. As explained above, the fibreboard drum may be of laminated or nonlaminated structure. If laminated, inner and outer plys are preferably of conventional kraft paper which may be either wet or dry finished. So, to, if the fibreboard is of nonlaminated construction, its opposite surfaces are wet or dry finished as may be required. In either construction, the surface of the fibreboard is preferably impervious to liquids, and the inner surface or in some instances both the inner and outer surfaces are lined with a protective coating of any conventional composition.
The drum containers are frequently used for packing such material as asphalt, rubber and the like which is poured in place in a liquid condition to be hardened upon cooling. For packaging such material, the interior surface of the drum is lined with any conventional coating material, i.e., silicone, polyethylene, polypropylene, that is commonly used for the purpose of rendering the drum impervious to absorption from the contents contained within the drum or moisture from outside ambient conditions. The tubular form is made from a fibreboard blank with its side edges overlapped and joined to any desired extent for forming the lap joint extending lengthwise of the tubular form. Adhesives, staples or other fastening means can be used to join the side edges.
Recently, it has been shown that other materials such as food slurries and the like can be conveniently packaged in fiberboard drums for shipping and storage. Other uses to which the fibreboard drums can be placed are obvious to one of ordinary skill in the art. In particular, there are in reality no limitations on the materials which can be retained or shipped by the fibreboard drums of this invention. In many instances, specific end uses require modifications of the innermost protective or barrier coating of the fibreboard to meet relevant Food and Drug Administration guidelines or the like, but in no instances are the technical problems with the formulation and use of such coatings serious. Therefore, for purposes of this application, it will be assumed that the improved fibre drum closure assembly can be used with any such material and the specific use of the drum or the particular material to be contained by the drum are not alleged to be inventive features herein.
Logically, it has been found that the effective commercial use of the fibre drum disclosed hereinabove requires both a bottom closure member and a top closure member. It has been known to use a metal disk as the bottom for drum members. The use of such bottom members and an apparatus for producing a container having a tubular fibreboard body portion and a metal disk bottom member is described by U.S. Pat. No. 3,057,265 issued to Leibreich in 1962. In this patent it is described how drums can be formed and a metal bottom seamed onto the bottommost edge of the tubular container member. In this fashion a fibreboard drum is formed having a sealed bottom member but having no top.
There have been a variety of previous attempts in the use and manufacture of a top closure member for use with fibreboard drums. The previous attempts to produce such drums consistently suffer from disadvantages. Among these are that the top member did not provide a good seal and, therefore, could not be used for materials which could leak or which could be spoiled or otherwise disadvantages by exposure to the atmosphere. Secondly, many of the prior art attempts to form a top closure member did not have stacking capabilities which provide a substantial advantage in the shipping and storage of the fibreboard drums once they have been filled. Third, many of these prior art top closure members required actual assembly on a machine such as a seaming machine. This is, of course, extremely cumbersome, expensive and not time efficient.
It has further been shown that when fibre drums are used for food packaging and shipped in stacked configuration that grooves used for stacking purposes are convenient receptacles for dirt, water and other material which may find its way into the packaged food when the top is removed from the drum. In this regard, see commonly assigned U.S. Pat. No. 4,182,475, issued Jan. 8, 1980 to Freund to a similar drum closure assembly. Finally, the prior closure members either did not hold the fibreboard drum round for purposes of filling. As can be appreciated, it is necessary for the fibreboard drum to be held in a substantially round configuration during filling so that the maximum amount of material can be inserted into each drum. The drum closure assembly of this invention solves all of these and other problems which have been appreciated by the prior art.
Other patents of which the applicants are aware which deal with the concept of closing drums include:
U.S. Pat. No. 801,382 to Keyes (1905); PA1 U.S. Pat. No. 1,528,489 to Snell (1926); PA1 U.S. Pat. No. 1,725,525 to Knodolf (1929); PA1 U.S. Pat. No. 3,054,548 to Scott (1962); PA1 U.S. Pat. No. 3,297,193 to Stevens (1967); PA1 U.S. Pat. No. 3,358,875 to Ekstrom (1967); PA1 U.S. Pat. No. 3,843,013 to Brooks (1974); PA1 U.S. Pat. No. 3,880,288 to Hunter (1975); PA1 U.S. Pat. No. 4,030,850 to Hyde (1977); PA1 U.S. Pat. No. 4,042,169 to Burgdorf (1977); PA1 U.S. Pat. No. 4,094,460 to Scanga et al. (1978); PA1 U.S. Pat. No. 4,166,548 to Crisci (1979); PA1 Australian Pat. No. 261, 090 to Hosking (1964).
Of these additional patents, Scanga et al., U.S. Pat. No. 4,094,460, represents an effort to provide a closure assembly which can be heat sealed. Such heat sealing devices require heat sealable discs and the like and in general must withstand severe pressure and temperature gradients. For this reason, oftentimes the prior art requires an outward expansion of the drum edge as is shown more particularly by U.S. Pat. No. 4,094,460. This is a disadvantage to standard KD drum production as such a requirement severely limits the use of mass production techniques and limits the "knocked-down" configuration of the drums themselves. Heat sealing containers additionally require heat sealable surfaces which severely limits the use of the appropriate guide means and locking means. In addition, the expanded groove shown by the prior art severely limits the production capabilities of injection molding apparatus which is traditionally used in the manufacture of this type of apparatus.